1. Field of the Invention
The present invention relates to an image formation method wherein an image is formed with powder toner and liquid ink, and to an apparatus for carrying out the method.
2. Description of the Related Art
Conventional representative examples of methods for forming color images with printers, photocopiers, facsimile apparatuses, and so forth, include electrophotography and ink jet image formation.
With electrophotography, for example, a toner image is formed on a photosensitive drum by charging, exposing, and developing means disposed around the photosensitive drum, the toner image is transferred onto a recording medium, and finally the toner image on the recording medium is fixed by fixing means. Monotone arrangements can be configured relatively small, but color electrophotography apparatuses results in a large apparatus and high costs.
On the other hand, with the later ink jet method, ink is directly discharged onto the recording medium from a recording head to form an ink image, so color apparatuses can be configured with relatively small arrangements, but there are various problems, such as insufficient rub-resistance and water resistance of the printed article immediately following printing, and also, in the event of using plain paper for the recording medium, bleeding can occur between the colors, deteriorating the image quality in comparison with electrophotography.
While image formation methods having both electrophotography image formation means and ink jet image formation means have been proposed to solve these problems, there is still room for improvement such as with the following points:                1) The ink is sometimes repelled by the toner at adjacent or overlapping portions between the toner image and the ink image.        2) The image may bleed due to mixture of color inks.        3) The recording medium may become bloated immediately following application of the color medium to a paper recording medium or the like, and depending on the degree of bloating, the recording medium may become undulated, leading to creasing or curling.        4) In the event of performing thermal fixing after forming the toner image, and then forming an image by ink jet image formation, the recording medium formed of paper or the like may shrink, leading to imperfectly aligned toner and ink images.        
For example, U.S. Pat. No. 5,081,596 proposes a system wherein an electrophotography (laser printer) unit and an ink jet unit are combined, but no means for avoiding the above problems are mentioned. Also, Japanese Patent Laid-Open No. 7-205542, Japanese Patent Laid-Open No. 7-223362, and Japanese Patent Laid-Open No. 11-277814 disclose methods for forming an image with color water-based ink following formation of an image with black toner, but these still have not solved the above problems.
Specifically, in the event of recording an ink jet image with water-based ink following forming and fixing a toner image, as described in Japanese Patent Laid-Open No. 7-223362, the ink is repelled by the toner image. On the other hand, in the event of switching between formation of dots with toner and formation of dots with ink for the same color, based on the attributes of an object image as described in Japanese Patent Laid-Open No. 11-277814, the apparatus becomes complex.